docs: def _sigma_pi_hiE(self, Tp, a):
          """
          General expression for Tp > 5 GeV (Eq 7)
          """
          m_p = self._m_p
          csip = (Tp - 3.0) / m_p
          m1 = a[0] * csip ** a[3] * (1 + np.exp(-a[1] * csip ** a[4]))
          m2 = 1 - np.exp(-a[2] * csip ** 0.25)
          multip = m1 * m2
          return self._sigma_inel(Tp) * multip